(a) Technical Field of the Invention
This invention relates generally to a method and apparatus for mounting a utility device or system onto existing or new towers. Such devices or systems may include a wind power generation system, a cellular communication system, or a system that receives, transmits or transfers radio or television signals, or other system.
The advantage of this invention is that it allows such devices or systems to be mounted onto an existing tower.
In one embodiment, this invention allows a wind turbine system to be mounted onto an existing cellular communication tower, or a radio and television transmission tower. This localizes the generation of wind power, and reduces the per capita cost of generation. In particular, it facilitates the mounting of wind turbine generation systems onto remote communication towers at a very low cost. The apparatus in this invention also allows other digital communication antennae to be mounted onto an existing tower.
(b) Description of the Relevant Art
The pursuit of renewable and sustainable energy sources is of utmost importance to the survival of our civilization. Recent global events, like the turmoil in the middle east and the leak at the nuclear power plants in Japan, in the aftermath of the earthquake and tsunami, underscore the immediate need for inexpensive means to generate power locally.
Wind power has been the fastest-growing source of new electric power generation for several years. According to the Department of Energy, wind power generation in 2009 was up 33.5 percent over the prior year. The 2005 Energy Policy Act provided interest-free financing via Clean Renewable Energy Bonds to government entities investing in wind. Farmers, ranchers and other rural businesses have also been benefited by the grant and loan guarantee provisions for wind projects, in Section 9006, under Title IX of the 2002 and 2008 Farm Bills. Several states provide incentives for projects involving renewable sources of energy, including wind projects. A listing of such incentives is available at the Database of State Incentives for Renewables and Efficiency (http://www.dsireusa.org/index.cfm?EE=0&RE=1).
Antenna poles or towers have been used for a long time now. These towers are generally used to transmit, receive and forward radio and television signals. Recently, with the increase in cellular communication, microwave towers have proliferated on the landscape, even in rural areas. Such poles or towers range in height from 80 to 220 feet or more.
Wind turbines are a clean and green alternative to coal and nuclear power plants. These turbines are mounted at higher elevations or on top of towers because that is where the average wind speed is high. This is important since the power generated by a wind turbine is roughly proportional to the cube of the average wind speed.
One of the major drawbacks of using wind turbines is the installation cost of a tower to support such an apparatus. This cost is large enough to reduce the overall efficacy and cost-effectiveness of using this alternate form of energy.
Another drawback is that large-scale wind power generation requires a large number of wind towers, with large wind turbines, which subsequently requires a large tract of land. The cost of setting up such farms, including the cost of leasing large tracts of land, again reduces the overall efficacy and cost-effectiveness of using this alternate form of energy.
Therefore, there is a need to make the generation of wind power less expensive. Since the cost of installing towers is a substantial deterrent, there is a need to have an apparatus that allows wind turbines to be mounted onto existing towers. Also, instead of large wind farms, it may be more economical to generate power off-grid for smaller communities. Since cellular communication towers and towers for the transmission of radio and television signals are widespread throughout the landscape, including rural landscapes, it is desirable to mount wind turbines onto such existing towers. It should be noted that the general concept for combining wind turbine towers and cellular antenna is well known in the art.
An apparatus that modifies existing wind towers to also accommodate communications functionality is disclosed in U.S. Pat. No. 7,138,961 by Sievert. In this invention, the wind tower design is largely unchanged. However, there is an optional add-on feature that is able to operate as, or contain the functionality of, a communications tower. The focus of the discussion of Sievert's invention relates to cellular signal transmission.
A wind turbine for a power transmission tower is disclosed in U.S. Patent Application Publication No. 2005/0230980 by Brunet. This invention relates to an improved wind turbine that may be installed onto an existing power grid infrastructure. The focus of this invention is more on weaning off the power generated by a wind turbine directly to an existing power grid.
The construction of an antenna tower and a method to couple an antenna array to a tower is disclosed in U.S. Pat. No. 7,576,705 by Greenfield et al. The antenna mounting apparatus is fastened onto the poles of a three-pole, lattice-type tower.
An antenna platform and a mounting apparatus for rotatably mounting the antenna platform to the tower is disclosed in U.S. Pat. No. 6,710,751 by Ianello et al. This invention allows the antenna platform to rotate about a lattice tower. The rotational mechanism overcomes the difficulty imposed by the triangular shape of the lattice tower. The platform itself has a triangular shape, and sits on a ring that facilitates the rotational movement. Although the platform may be set at any desired position about a 360-degree azimuth, the platform's rotation is restricted to at most a 120-degree arc.
While such a limited range of rotation may suffice for cellular communication signals, this design is not compatible with the functioning of a wind turbine. Wind may travel in any direction. Therefore, it is desirable to design a platform that is capable of rotating the entire 360-degrees, to facilitate the movement of the rotary blades of a wind turbine with respect to wind blowing in different directions. Moreover, the design should also facilitate ease of rotation.
An antenna mounting platform for a monopole tower is described in U.S. Pat. No. 5,467,955 by Beyersmith. The essential feature of this invention is that it allows brackets to be releasably mounted along the length of a monopole at any desired height.
In U.S. Pat. No. 6,052,092, Davis et al. describe a platform for a wireless telecommunication antenna. The platform is mounted at the top of an electric power transmission tower. Although the platform may be rotatably adjusted by using a nut and bolt configuration, the platform itself remains stationary while in use.
While all the inventions mentioned above are directed at various apparatus that support the multiple use of towers, they fail to overcome the substantial technical hurdles of the prior art. Providing flexibility in the range of rotation allows the use of a single tower for multiple purposes. The present invention provides such capability.
The present invention provides one or more platforms that may be mounted onto already existing towers. These platforms may rotate about the longitudinal axis of the tower, up to the full 360-degree range. Moreover, these platforms may support a variety of devices or systems, including wind turbines, cellular communication antennae, and other devices to receive, transmit or transfer radio and television signals. The rotation itself is very smooth, facilitating easy movement of the platform in response to the wind direction. Finally, this invention allows for a continuous and uninterrupted electrical connection between the rotating unit of the device and the stationary unit of the device. In the case of a wind power generation system, the rotating unit would be a wind turbine, while the stationary unit could be a generator. In the case of a cellular transmission system, or a radio and television signal transmission or receiving system, the rotating unit would be an antenna and the stationary unit could be a signal transmitter or receiver.